Weight gain in 1st trimester question

Kara

I'm currently 10w1d and I have a normal BMI. I have already gained 4 lbs, and I still have 4 weeks to go until I get to the 2nd trimester. Is it normal to have already put on weight? I read online that you really don't need to gain weight at all in the first trimester so I'm just already nervous that I'm gaining too much.